Cytochrome P450 catalyzes many enzymatic reactions for various kinds of substrates, i.e., an oxidative, peroxidative, and reductive metabolism of endogenous and xenobiotic substrate. Specifically, plant P450 participates in various biochemical pathways for the synthesis of plant products including phenylpropanoids, alkaloids, terpenoids, lipids, cyanogenic glycosides and glucosinolates (Chapple, Annu. Rev. Plant Physiol. Plant Mol. Biol. 1989, 49: 311-343).
Cytochrome P450 is also known as P450 hemi-thiolate protein and functions as a final oxidizing enzyme in multi-component electron transfer chains that is called P450-comprising monooxygenase system. As a specific catalytic reaction, it includes demethylation, hydroxylation, epoxidation, N-oxidation, sulfooxidation, N-, S- and O-dealkylation, deamination, desulfation, and reduction of azo, nitro and N-oxide group.
Various roles of P450 enzyme of nicotiana plants are related to a diversity of plant metabolites such as phenylpropanoids, alkaloids, terpenoids, lipids, cyanogenic glycosides, and glucosinolates and a host of other chemical entities. During the last couple of years, it has been confirmed that some of the P450 enzymes have an effect on a constitution of plant metabolites in plants.
Based on the-above described prior art, inventors of the present invention found that, while studying the functions of cytochrome P450, cytochrome P450 originating from Arabidopsis thaliana can improve seed size of plants or storage protein content in plants or increase water stress resistance of plants, and therefore completed the present invention.